Abstract

Response surface methodology was used to study the effect of egg albumen (5–15 g), vegetable oil (5–15 g), and corn bran (5–15 g) on sensory and textural (firmness and toughness) quality of chicken nuggets cooked by the oven, steam, and microwave methods. The egg albumen and vegetable oil had a positive linear effect but corn bran had a negative linear effect at p<0.01 on sensory overall acceptability scores of nuggets. Firmness and toughness scores were increased significantly (p<0.01) with the increase in corn bran level in the formulation. The optimum level of egg albumen, vegetable oil, and corn bran were obtained and validated. Cooking methods also affected the sensory and textural quality of nuggets. Steam cooked nuggets had higher values of sensory scores than oven and microwave cooked nuggets. Oven cooked nuggets showed higher values of firmness and toughness than steam and microwave cooked nuggets. Results of this study suggest that emulsion based meat products can be enriched with dietary fiber source like corn bran without compromising the sensory and textural quality of the products.

Introduction

Non-meat ingredients plays important role in deciding the quality of emulsion based meat products. Generally processed meat products have good nutritional quality but lacks in dietary fiber content. The diets deficient in dietary fiber are associated with several health problems (WHO/FAO, 2003). The consumption of fiber-rich diets has been related to decreased incidence of several diseases and has a positive effect on health (Dhingra et al., 2012; Kaushik et al., 2015; Kumar et al., 2013). The use of cereals bran has been increased in a variety of emulsion based meat products in recent years. Previously, wheat and oat bran were added in chicken meat patties (Talukder and Sharma, 2010), rice bran in the emulsified pork meatballs (Huang et al., 2005), wheat bran in chicken nuggets (Pathera et al., 2017), corn bran in chicken sausages (Yadav et al., 2016), and wheat bran in beef patties (Sariçoban et al., 2009). Cereals bran acts as a functional ingredient in meat products and it also helpful in reducing the cost of meat products. But, instead of these beneficial functions, the use of bran reduces the overall sensory quality of meat products. It is necessary to maintain the sensory quality of meat products and use of other ingredients like egg albumen and vegetable oil are needed to overcome the negative effect of bran on sensory quality. Kalaikannan et al. (2007) improved the sensory scores of chicken patties by the addition of egg albumen, which contributed to enhancing the flavor, texture, and juiciness of the product. Verma et al. (2009) reported an increase in sensory scores as the level of sunflower oil incorporation increased in chicken nuggets.

The optimum level of ingredients can be obtained using the statistical tool response surface methodology. Previously, some researchers had studied the effects of ingredients on products quality and optimized the formulation for emulsion based meat products (Murphy et al., 2004; Pathera et al., 2017; Sariçoban et al., 2009). The type of cooking techniques affects the quality of meat products. The effect of dry or moist cooking on products quality was observed by Cholan et al. (2011) in chicken patties cooked by oven, steam, microwave, and frying techniques. Talukder and Sharma (2010) also studied the quality characteristics of steam and oven cooked patties incorporated with fiber. In this view, the present study was designed to optimize the level of egg albumen, vegetable oil, and corn bran in chicken nuggets prepared by oven, steam, and microwave cooking methods.

Materials and Methods

Egg albumen

Eggs were procured from local market and kept under refrigerated (4±1°C) storage. Eggs were broken and albumen was separated from yolk manually for incorporation in the formulation.

Corn bran was obtained from Vitarich Agro Food (India) Limited, Kolkata, India. Microwave stabilization of corn bran was done as per method developed by Ramezanzadeh et al. (2000). The bran was grinded in an electrical grinder, passed through 1 mm sieve, packed in an airtight container and stored in a freezer (–18°C) for further use.

Broiler chicken

Broiler birds of 1.5–2.0 kg weight and 6–7 weeks age reared under similar feeding and managemental conditions were slaughtered and dressed as per the standard procedure in the slaughter house of Department of Livestock Products Technology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, India. Carcasses were washed thoroughly; breast and leg cuts were separated. Both the cuts were deboned manually after trimming of visible fat and connective tissue. Deboned meat from both the cuts was mixed in equal proportion and stored in a freezer (–18°C) for further use.

Experimental design

Response surface methodology was used to study the effect of ingredients variable namely egg albumen, vegetable oil, and corn bran. The experiments were designed using the software, Design Expert trial version 9 (State-Ease, Minneapolis, MN). The experiments were based on Box-Behnken experimental design (Box and Behnken, 1960). Values of independent variables at three levels of the Box-Behnken design are presented in Table 1. The experimental design involved 17 experiments as presented in Table 2 in coded levels. Experiments were conducted for three different cooking methods viz. oven, steam, and microwave separately by using same experimental design. For each response assessed, the variables were divided into linear, interaction and quadratic effect. The responses (sensory overall acceptability, firmness, and toughness) for different experimental combinations were assessed by a second-degree polynomial equation.

Where Y is the estimated response, the coefficients of the polynomial were represented by β0 (constant), β1, β2, β3 (linear effects); β12, β13, β23 (interaction effects); β11, β22, β33 (quadratic effects). The adequacy of the generated model was determined by evaluating the lack of fit, coefficient of correlation (r2), and the Fisher test value (F-value) obtained from the analysis of variance (ANOVA). The regression coefficients were used to generate the graphical presentation of response surface three-dimensional plots by using the Design Expert trial version 9 (State-Ease, Minneapolis, MN).

Nuggets samples were warmed before serving and coded samples were presented before panelists (a semi-trained panel of research scholars and faculty members of the Department of Livestock Products Technology, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, India). Panelists were experienced in sensory analysis of meat products. Sensory overall acceptability scores (in terms of color and appearance, flavor, texture, tenderness, and juiciness) were evaluated using 8-point descriptive scale, where 8 indicate extremely acceptable and 1 indicates extremely unacceptable.

Texture analysis

Nuggets samples were subjected to texture analysis at room temperature. Results were measured in terms of Firmness (N) and toughness (N.sec) using TAHD Plus Texture Analyser (Stable Micro Systems, England). Cubic samples of 15×15×15 mm size were cut by Warner Bratzler cutting blade having rectangular notch. Force time cutting curves were obtained with a 50 kg load cell applied at a cross-head speed of 2 mm/s. The maximum force required to cut the sample was taken as an index of firmness and the total positive area under the curve was taken as toughness.

Statistical analysis and optimization

The statistical analysis was performed by same software, Design Expert trial version 9 (State-Ease, Minneapolis, MN). The significance of parameters for each response was assessed using the F test. Numerical multi-response optimization technique was applied to determine the optimum level of egg albumen, vegetable oil, and corn bran for three different formulations. The independent variables (egg albumen, vegetable oil, and corn bran) and dependent variables (OAA, firmness and toughness) were kept within experimental range with maximum desirability (Prasad and Singh, 2014). The desirability was calculated by following equation and the highest desirability was selected.

The results of texture analysis of nuggets were presented in terms of firmness and toughness. The firmness of oven, steam, and microwave cooked nuggets varied from 9.36 to 13.65, 7.72 to 12.53, and 7.85 to 12.22 N respectively (Table 1). The model F-values indicated that model is significant and values of r2, adjusted r2, and adequate precision indicates that the model can be used for prediction purpose (Table 3). In oven cooked nuggets, albumen and oil had no significant effect on firmness values but corn bran had a significant (p<0.01) linear effect on firmness values. In the case of steam and microwave cooked nuggets, it could be observed from Table 3 that increase in albumen or oil decreased the firmness as the coefficient of albumen (x1) and oil (x2) are negative. The positive coefficient of corn bran (x3) indicates that adding the corn bran increases the firmness of nuggets (Fig. 2). The interaction effects of albumen and oil (x12); oil and corn bran (x23) were found significant (p<0.05) in steam and microwave cooked nuggets respectively. Jung and Joo (2013) reported a decrease in hardness with increased level of soybean oil in pork patties. Murphy et al. (2004) observed a decrease in the force value with increased level of fat in pork sausage. Yadav et al. (2016) reported significantly (p<0.05) higher hardness and shear press values in corn bran added chicken sausages. Pathera et al. (2017) observed an increase in firmness of chicken nuggets with an increase in wheat bran level in the formulation. Similarly, wheat bran addition increased the hardness and firmness values in beef patties (Sariçoban et al., 2009) and meat balls (Yilmaz, 2005) respectively. Yilmaz and Dağlıoğlu (2003) also reported similar results of texture in oat bran added meat balls.

The toughness of oven, steam, and microwave cooked nuggets varied from 67.39 to 97.65, 53.82 to 86.67 and 54.86 to 86.14 N.sec respectively. The significant terms of the coefficient obtained by analysis of variance were presented in Table 3. The trend for toughness was almost similar to data obtained for firmness. The toughness of nuggets decreased with the increase in albumen or oil level. The increase in corn bran significantly (p<0.01) increased the toughness values of all the nuggets. Fig. 3 also depicted the positive linear effect of corn bran on toughness values of nuggets. Pathera et al. (2017) noticed an increase in toughness values of chicken nuggets with an increase in wheat bran level in the formulation. Huang et al. (2005) observed an increase in hardness value of pork meat balls with the increase in rice bran level. Talukder and Sharma (2010) also reported a higher shear press value in chicken meat patties incorporated with wheat bran.

The cooking methods affected the textural quality of oven, steam, and microwave cooked nuggets. The firmness and toughness values of oven cooked nuggets were found higher than steam and microwave cooked nuggets. The effect of dry heat might be the reason for higher values of firmness and toughness of oven cooked nuggets. Another reason for the harder texture of oven cooked nuggets might be the more moisture loss in the oven cooking in comparison to other cooking methods. The firmness and toughness values of steam and microwave cooked nuggets were found almost in similar range. Talukder and Sharma (2010) noticed significantly (p<0.05) lower shear press values of steam cooked patties than oven cooked patties. Pathera et al. (2017) also observed the similar effect of cooking methods on textural quality of dietary fiber enriched chicken nuggets.

Product optimization

The numerical multi-response optimization technique with desirability function in Design Expert software was used to estimate the optimum level of egg albumen, vegetable oil, and corn bran. Three optimum formulations for nuggets having desirability of 1 were determined for each cooking method. These optimum formulations were used to manufacture nuggets by respective cooking methods. The predicted values of response were validated against actual values of responses at the optimized condition of experiments. The formulations for nuggets having least deviation (less than 5%) in actual values of response against predicted values were presented in Table 4 and found best among respective 3 optimum formulations.

Table 4. Predicted and actual values of responses at the optimized condition of experiments

Conclusion

The sensory and texture are important quality parameters for development of meat products. Increasing level of egg albumen or vegetable oil increased the sensory scores and decreased the firmness and toughness values of nuggets. The increase in corn bran level decreased the sensory scores and increased the firmness and toughness values of nuggets. Therefore, optimum levels of egg albumen, vegetable oil, and corn bran were determined based on the sensory and textural quality of nuggets. The results obtained would be useful for the meat products manufacturer which tends to enrich the dietary fiber in meat products having good sensory and textural quality.

Acknowledgements

The authors would like to thank Department of Livestock Products Technology, Lala Lajpat Rai University of Veterinary and Animal Sciences (Haryana, India) for technical assistance during this study.

References

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Box GEP, Behnken DW. Some new three level designs for the study of quantitative variables. Technometrics. 1960; 2:455-475.